Accident summary

On 11 June 1987 a team of four contractors was cleaning a crude oil
storage tank at the Dalmeny Oil Storage Terminal. The tank was of the
floating roof type and the roof had been lowered due to the tank being
empty. It was resting on a series of 219 support pillars. Three of the
contractors worked inside the tank with one on duty outside along with a BP
employee.

The tank had been emptied of its contents and three roof manhole covers
opened to allow natural ventilation. However, the evolution of a vapour with
the risk of forming an explosive atmosphere was not considered sufficient to
merit either mechanical ventilation or rigorous monitoring of the vapour
concentrations within the tank. As a precaution though, the workers were
required to wear airline-breathing apparatus supplied by a compressor
located outside the tank bund.

At 13:20 hours the outside man looked in and saw a ring of fire
surrounding the three men. Two of the employees managed to escape the fire
but the third man died from the effects of asphyxiation and burns. The fire
escalated rapidly with flames and smoke coming out of the open man ways.

The cause of the accident was one of the contractors smoking inside the
oil tank. It was apparently common practice for the workers to remove their
breathing apparatus while inside the tank, with some workers choosing to
smoke while the supervisor was not looking. On this occasion one of the men
working in the tank had dropped a lit cigarette on to the floor where it had
ignited the crude oil.

Failures in technical measures

Several workers disregarded basic safety procedures, resulting in a
lit cigarette being dropped inside the storage tank.
Terminal rules required all matches and lighters to be surrendered at
the security gate, but this was not enforced.

The contracting staff working inside the storage tank had not been
properly informed of the toxic risks of working without the appropriate
breathing apparatus and the potential for a flammable vapour at the oil
surface.

References

Health and Safety Executive, ‘The fires and explosion at BP Oil
(Grangemouth) Refinery Ltd. A report of the investigations by the Health and
Safety Executive into the fires and explosion at Grangemouth and Dalmeny,
Scotland, 13 March, 22 March and 11 June 1987’, ISBN: 0 11 885493 3, 1989.